文章目录
一、ElasticSearch是什么
ElasticSearch(ES)是一个基于Lucene构建的开源、分布式、restful接口全文搜索引擎，一个分布式文档数据库。
二、ElasticSearch的基本概念
ES与MySql概念类比对照
| ES | MySQL |
|---|---|
| 索引 | 数据库 |
| 类型 | 表 |
| 文档 | 记录 |
三、ElasticSearch可以用来做什么
1、网站内部搜索引擎
2、结合FileBeat、Logstash 、ElasticSearch、Kibana 可以实现日志的搜集、存储、查询
四、ElasticSearch安装部署
1、home路径下新建es-cluster目录
mkdir es-cluster
2、新建docker-compose.yml内容如下
version: '2.2'
services:
es01:
image: elasticsearch:7.12.1
container_name: es01
environment:
- node.name=es01
- cluster.name=es-docker-cluster
- discovery.seed_hosts=es02,es03
- cluster.initial_master_nodes=es01,es02,es03
- "ES_JAVA_OPTS=-Xms512m -Xmx512m"
volumes:
- data01:/usr/share/elasticsearch/data
ports:
- 9200:9200
networks:
- elastic
es02:
image: elasticsearch:7.12.1
container_name: es02
environment:
- node.name=es02
- cluster.name=es-docker-cluster
- discovery.seed_hosts=es01,es03
- cluster.initial_master_nodes=es01,es02,es03
- "ES_JAVA_OPTS=-Xms512m -Xmx512m"
volumes:
- data02:/usr/share/elasticsearch/data
ports:
- 9201:9200
networks:
- elastic
es03:
image: elasticsearch:7.12.1
container_name: es03
environment:
- node.name=es03
- cluster.name=es-docker-cluster
- discovery.seed_hosts=es01,es02
- cluster.initial_master_nodes=es01,es02,es03
- "ES_JAVA_OPTS=-Xms512m -Xmx512m"
volumes:
- data03:/usr/share/elasticsearch/data
networks:
- elastic
ports:
- 9202:9200
volumes:
data01:
driver: local
data02:
driver: local
data03:
driver: local
networks:
elastic:
driver: bridge
3、设置虚拟地址空间数量，不然es启动报错
3.1、错误信息：
max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]
3.2、打开配置文件：
sudo vim /etc/sysctl.conf
3.3、增加如下配置：
vm.max_map_count=262144
3.4、刷新最新配置：
sudo sysctl -p
4、启动es
docker-compose up -d
5、查看日志
docker logs -f es01
6、停止es集群
docker-compose stop
7、浏览器访问http://localhost:9200/、http://localhost:9201/、http://localhost:9202/
{
"name" : "es01",
"cluster_name" : "es-docker-cluster",
"cluster_uuid" : "xvagkyFNSXCfty78yDZwUg",
"version" : {
"number" : "7.12.1",
"build_flavor" : "default",
"build_type" : "docker",
"build_hash" : "3186837139b9c6b6d23c3200870651f10d3343b7",
"build_date" : "2021-04-20T20:56:39.040728659Z",
"build_snapshot" : false,
"lucene_version" : "8.8.0",
"minimum_wire_compatibility_version" : "6.8.0",
"minimum_index_compatibility_version" : "6.0.0-beta1"
},
"tagline" : "You Know, for Search"
}
五、go连接ElasticSearch
1、go es客户端安装
go get github.com/elastic/go-elasticsearch/v7
2、github demo
package main
import (
"bytes"
"context"
"encoding/json"
"log"
"strconv"
"strings"
"sync"
"github.com/elastic/go-elasticsearch/v7"
"github.com/elastic/go-elasticsearch/v7/esapi"
)
func main() {
log.SetFlags(0)
var (
r map[string]interface{
}
wg sync.WaitGroup
)
// Initialize a client with the default settings.
//
// An `ELASTICSEARCH_URL` environment variable will be used when exported.
// 配置es地址
cfg := elasticsearch.Config{
Addresses: []string{
"http://localhost:9200", "http://localhost:9201", "http://localhost:9202"},
}
es, err := elasticsearch.NewClient(cfg)
if err != nil {
log.Fatalf("Error creating the client: %s", err)
}
// 1. Get cluster info
// 查询集群信息
res, err := es.Info()
if err != nil {
log.Fatalf("Error getting response: %s", err)
}
// Check response status
if res.IsError() {
log.Fatalf("Error: %s", res.String())
}
// Deserialize the response into a map.
if err := json.NewDecoder(res.Body).Decode(&r); err != nil {
log.Fatalf("Error parsing the response body: %s", err)
}
// Print client and server version numbers.
log.Printf("Client: %s", elasticsearch.Version)
log.Printf("Server: %s", r["version"].(map[string]interface{
})["number"])
log.Println(strings.Repeat("~", 37))
// 2. Index documents concurrently
// 创建索引
for i, title := range []string{
"Test One", "Test Two"} {
wg.Add(1)
go func(i int, title string) {
defer wg.Done()
// Build the request body.
var b strings.Builder
b.WriteString(`{"title" : "`)
b.WriteString(title)
b.WriteString(`"}`)
// Set up the request object.
req := esapi.IndexRequest{
Index: "test",
DocumentID: strconv.Itoa(i + 1),
Body: strings.NewReader(b.String()),
Refresh: "true",
}
// Perform the request with the client.
res, err := req.Do(context.Background(), es)
if err != nil {
log.Fatalf("Error getting response: %s", err)
}
defer res.Body.Close()
if res.IsError() {
log.Printf("[%s] Error indexing document ID=%d", res.Status(), i+1)
} else {
// Deserialize the response into a map.
var r map[string]interface{
}
if err := json.NewDecoder(res.Body).Decode(&r); err != nil {
log.Printf("Error parsing the response body: %s", err)
} else {
// Print the response status and indexed document version.
log.Printf("[%s] %s; version=%d", res.Status(), r["result"], int(r["_version"].(float64)))
}
}
}(i, title)
}
wg.Wait()
log.Println(strings.Repeat("-", 37))
// 3. Search for the indexed documents
// 查询信息
// Build the request body.
var buf bytes.Buffer
query := map[string]interface{
}{
"query": map[string]interface{
}{
"match": map[string]interface{
}{
"title": "test",
},
},
}
if err := json.NewEncoder(&buf).Encode(query); err != nil {
log.Fatalf("Error encoding query: %s", err)
}
// Perform the search request.执行查询
res, err = es.Search(
es.Search.WithContext(context.Background()),
es.Search.WithIndex("test"),
es.Search.WithBody(&buf),
es.Search.WithTrackTotalHits(true),
es.Search.WithPretty(),
)
if err != nil {
log.Fatalf("Error getting response: %s", err)
}
defer res.Body.Close()
if res.IsError() {
var e map[string]interface{
}
if err := json.NewDecoder(res.Body).Decode(&e); err != nil {
log.Fatalf("Error parsing the response body: %s", err)
} else {
// Print the response status and error information.
log.Fatalf("[%s] %s: %s",
res.Status(),
e["error"].(map[string]interface{
})["type"],
e["error"].(map[string]interface{
})["reason"],
)
}
}
if err := json.NewDecoder(res.Body).Decode(&r); err != nil {
log.Fatalf("Error parsing the response body: %s", err)
}
// Print the response status, number of results, and request duration.
log.Printf(
"[%s] %d hits; took: %dms",
res.Status(),
int(r["hits"].(map[string]interface{
})["total"].(map[string]interface{
})["value"].(float64)),
int(r["took"].(float64)),
)
// Print the ID and document source for each hit.
for _, hit := range r["hits"].(map[string]interface{
})["hits"].([]interface{
}) {
log.Printf(" * ID=%s, %s", hit.(map[string]interface{
})["_id"], hit.(map[string]interface{
})["_source"])
}
log.Println(strings.Repeat("=", 37))
}